JPH07223981A - Method for producing hydrofluorocarbon - Google Patents

Abstract

PURPOSE:To obtain the subject hydrofluorocarbon under a low pressure in a short time in an extremely good reaction rate and in good selectivity by reacting a specific iodofluorocarbon with a reducing agent in a gaseous phase. CONSTITUTION:An iodofluorocarbon of formula, InRfI (n is 0, 1; when n is 0, Rf is 2-12C polyfluoroalkyl; when n is 1, Rf is 2-12C polyfluoroalkylene) is reacted with a reducing agent in a gaseous phase to obtain the objective carbon of formula, HnRfH. The reducing agent is hydrogen gas or an organic compound having hydrogen atoms bound to the carbon atoms, and the organic compound is preferably a 1-3C alcohol compound or a 1-3C carboxylic acid compound, especially methanol, ethanol or formic acid. The reaction is preferably performed in the absence of a catalyst or in the presence of a hydrogenation catalyst containing palladium, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel method for producing hydrofluorocarbons.

[0002]

2. Description of the Related Art The following reports have been made on a method for synthesizing a hydrofluorocarbon using iodofluorocarbon as a starting material.

Method of reduction in the presence of zinc (J. Fluorine
Chem., 6,297,1975). A method of synthesizing by a reaction using a Grignard reagent (J. Fluorine Chem., 3,247,1973). Method of synthesis by liquid-phase reduction reaction using hydrogen and Raney nickel catalyst (Ger. Offen. 2,060,041, J. Chem. Soc., 3761, 1
953). Method of synthesis by reduction reaction using sodium hypophosphite and palladium or platinum catalyst (J. Fluorine Ch
em., 55, 101, 1991). Method of reacting with alcoholic KOH (J. Chem. Soc., 3761, 1953). Method of reacting with alkali metal hydroxide in methanol (EP 0,449,516 A1
).

[0004]

However, since the above-mentioned conventional methods are all liquid phase reactions and batch reactions, the productivity is poor, and a large amount of combustible organic solvent is used in the reaction. There was a problem that it was necessary or that high-pressure hydrogen had to be used.

[0005]

Means for Solving the Problems As a result of intensive studies on the efficient production method of hydrofluorocarbon using iodofluorocarbon as a starting material, the present inventor has found that
The inventors have found a method in which iodofluorocarbon is reacted in a gas phase to obtain hydrofluorocarbon continuously and with high selectivity and high yield.

That is, the present invention has the general formula I _n R _f I (wherein n is 0 or 1, and when n is 0, R
_f is a linear or branched polyfluoroalkyl group having 2 to 12 carbon atoms, and when n is 1, R _f is 2 to 2 carbon atoms.
It is 12 linear or branched polyfluoroalkylene groups. ), An iodofluorocarbon represented by the formula: H _n R _f H (where n and R _f are the same as above) characterized by reacting in the gas phase under the action of a reducing agent. The present invention provides a method for producing a hydrofluorocarbon represented by (1).

The iodofluorocarbon which is a raw material of the present invention is a compound represented by the general formula I _n R _f I. However, in the formula, n is 0 or 1. When n is 0, R _f
Is a straight-chain or branched polyfluoroalkyl group having 2 to 12 carbon atoms, and preferably has 3 to 8 carbon atoms. When n is 1, R _f is a linear or branched polyfluoroalkylene group having 2 to 12 carbon atoms,
The case of having 3 to 8 carbon atoms is preferable.

R _f is preferably a polyfluoroalkyl group or a polyfluoroalkylene group in the case of (number of fluorine atoms) / (number of fluorine atoms + number of hydrogen elements) being 80 to 100%, and particularly perfluoroalkyl group. Groups or perfluoroalkylene groups are preferred. Further, R _f preferably has a linear structure, the linear perfluoroalkyl group is preferably CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ —, and the linear perfluoroalkylene group is —CF.
₂ CF ₂ CF ₂ CF ₂ - it is preferred.

Specific examples of the iodofluorocarbon include 1-iodo-1,1,2,2,2-pentafluoroethane ICF ₂ CF ₃ , 1-iodo-1,1,2,
2,3,3,4,4,4-nonafluorobutane I (CF
₂ ) ₄ F, 1-iodo-1, 1, _{2, 2, 3} , ₃ , ₄ ,
4,5,5,6,6,6-tridecafluorohexane I
(CF ₂ ) ₆ F, 1-iodo-1, 1, _{2, 2} , 3,
3,4,4,5,5,6,6,7,7,8,8,8- heptadecafluorooctanesulfonic _{I (CF 2) 8 F,} 2- iodo -1,1,1,2,3, 3,3-heptafluoropropane CF ₃ CFICF ₃ , 4-iodo-1,1,1,
2,3,3,4,4- octafluoro-2-trifluoromethyl-butane _{(CF 3) 2 CF (CF} 2) 2 I, 6-
Iodine-1,1,1,2,3,3,4,4,5,5
6,6-dodecafluoro-2-trifluoromethyl-hexane _{(CF 3) 2 CF (CF} 2) 4 I, 1,2- diiodo-1,1,2,2-tetrafluoroethane I (CF
₂ ) ₂ I, 1,4-diiodo-1,1,2,2,3
3,4,4-octafluorobutane I (CF ₂ ) ₄ I,
1,6-diiodo-1,1,2,2,3,3,4,4
5,5,6,6- dodecafluoro hexane I (CF _2)
6 I and the like, but are not limited thereto.

The present invention is characterized in that the above-mentioned iodofluorocarbon is reacted in the gas phase under the action of a reducing agent. The reducing agent is not particularly limited as long as it can be a hydrogen source in the reaction of the present invention, and an organic compound having a hydrogen atom bonded to a carbon atom or hydrogen is preferable, and particularly having a hydrogen atom bonded to a carbon atom. Organic compounds are preferred. The organic compound preferably has 8 or less carbon atoms, and particularly preferably 4 or less. The organic compound is preferably a hydrocarbon or an organic compound containing an oxygen atom, and the organic compound containing an oxygen atom includes a hydroxyl group, a carboxyl group, an ether group, a carbonyl group, a carbonyloxy group, and a formyl group. Organic compounds having at least one group selected from the group are preferred. Further, the organic compound is preferably at least one organic compound selected from the group consisting of alcohols, carboxylic acids, carboxylic acid derivatives, aldehydes, glycols, ethers, and hydrocarbons.

The alcohols in the present invention mean compounds having a monovalent hydrocarbon group and a hydroxyl group. As the monovalent hydrocarbon group, an alkyl group or an allyl group is preferable, and an alkyl group is particularly preferable. The alkyl group preferably has 1 to 10 carbon atoms, particularly preferably 1 to 6 carbon atoms, and further 1
~ 3 are preferred. The hydroxyl group of alcohols is preferably a primary hydroxyl group or a secondary hydroxyl group, and particularly preferably a primary hydroxyl group. As the alcohol in the present invention, a primary alcohol having the above-mentioned alkyl group and a primary hydroxyl group, or a secondary alcohol having the above-mentioned alkyl group and a secondary hydroxyl group is preferable, and a primary alcohol is particularly preferable because it is excellent in selectivity. preferable.

As the primary alcohol, methanol,
Ethanol, 1-propanol, 1-butanol, 2-
Methyl-1-propanol and the like can be mentioned, and in particular, methanol or ethanol is preferable from the viewpoint of excellent reactivity and productivity. As the secondary alcohol, 2-propanol, 2-butanol and the like are preferable.

As the alcohol, both primary alcohol and secondary alcohol may be used. 1 when using both
As the ratio of each of the primary alcohol and the secondary alcohol,
There is no particular limitation, and any ratio may be used.

The carboxylic acid in the present invention means an aromatic compound or an aliphatic compound having one or more carboxyl groups, and preferably has one carboxyl group. As the carboxylic acids, formic acid, acetic acid, propionic acid, malonic acid, succinic acid and the like are preferable, and formic acid is particularly preferable from the viewpoint of few by-products.

The carboxylic acid derivatives in the present invention mean compounds obtained by a dehydration reaction between the carboxyl group of the carboxylic acid and another compound. Examples thereof include carboxylic acid ester and carboxylic acid amide, and carboxylic acid ester is preferable.

As the carboxylic acid ester, alkyl esters of the above-mentioned carboxylic acids are preferable, and particularly methyl formate, ethyl formate, butyl formate, pentyl formate, methyl acetate, ethyl acetate, isobutyl acetate, isopropyl acetate,
Methyl propionate, methyl malonate, diethyl malonate, diethyl phthalate, di-2-ethylhexyl phthalate and the like are preferable, and ethyl acetate is preferable from the viewpoint of few by-products. Examples of the carboxylic acid amide include formic acid amide,
Acetamide, N, N-dimethylformamide, N, N-
Dimethylacetamide and the like are preferable.

The aldehydes in the present invention mean compounds having a formyl group. As aldehydes, formaldehyde, acetaldehyde and the like are preferable.

The ethers in the present invention mean a compound containing at least one structure in which two hydrocarbon groups are bonded to one oxygen atom. As the hydrocarbon group, an aliphatic hydrocarbon group is preferable. The hydrocarbon group preferably has about 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms. As ethers, diethyl ether, tetrahydrofuran, 1,4-dioxane and the like are preferable.

The glycols in the present invention include 2
It means an aliphatic compound having two hydroxyl groups bonded to two different carbon atoms, or a compound in which hydrogen of the two hydroxyl groups is substituted with a hydrocarbon group. As glycols, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, ethylene glycol dimethyl ether (glyme), diethylene glycol dimethyl ether (diglyme), propylene glycol dimethyl ether and the like are preferable.

The ketones in the present invention mean a compound having a carbonyl group bonded to two carbons. Preferred ketones are acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone and the like.

Hydrocarbons mean aliphatic hydrocarbons and aromatic hydrocarbons. As the aliphatic hydrocarbon, a saturated hydrocarbon having about 1 to 6 carbon atoms is preferable, and methane, ethane, propane, butane and the like are particularly preferable. As the aromatic hydrocarbon, a compound containing a benzene ring is preferable, a compound having a substituent bonded to the benzene ring is particularly preferable, and toluene, xylene and the like are preferable.

Among the above reducing agents, as the reducing agent in the present invention, alcohols and carboxylic acids are preferable, and alcohols are particularly preferable, from the viewpoints of easy handling, reactivity and economy.

The ratio of the raw material iodofluorocarbon to the above reducing agent can be varied widely. Normally, a stoichiometric amount of a reducing agent is used to reduce the iodine atom, but in order to almost completely react the raw material iodofluorocarbon, the stoichiometric amount is lower than the total equivalent amount of the iodine atom in the iodofluorocarbon. Two or more equivalents of reducing agent, which is a fairly large amount, may be used. In the usual case, it is preferable to use 1 to 5 times the equivalent of the reducing agent per 1 equivalent of the iodine atom in the raw material iodofluorocarbon. When the amount of the reducing agent is small, the reaction conversion rate decreases, and in addition to the general formula _{Rf- Rf} (wherein _Rf is a linear or branched polyfluoroalkyl having 2 to 12 carbon atoms). Group), which is not preferable because the dimerization product represented by

Further, in the reaction of the present invention, when the reducing agent is hydrogen, it is preferable that a hydrogenation catalyst is present. On the other hand, when the reducing agent is the above-mentioned organic compound, it may be carried out in the presence of a hydrogenation catalyst or in the absence of a catalyst, adjustment of the catalyst, complication of the structure of the reactor, Considering the post-treatment of the waste catalyst, it is preferable to carry out the reaction without a catalyst.

When a hydrogenation catalyst is present in the reaction of the present invention, the efficiency of reaction results can be increased. The hydrogenation catalyst is not particularly limited, and a known hydrogenation catalyst can be selected. Among these, in the present invention, it is preferable to allow a hydrogenation catalyst containing at least one element selected from the group consisting of alumina, activated carbon, zeolite, or a Group 8 element to be present, and particularly selected from a Group 8 element. It is preferred to have a catalyst present containing at least one element. Examples of the Group 8 element include palladium, ruthenium, rhodium, platinum, nickel, cobalt and iridium. Among these, in the present invention, it is preferable that the platinum group element such as ruthenium, rhodium, palladium, or platinum is contained from the viewpoint of durability of the catalyst, and particularly, the case where palladium is contained is preferable. In particular, a catalyst obtained by mixing or alloying palladium with gold or silver is preferable because not only the catalyst durability but also the reactivity becomes high.

Further, the hydrogenation catalyst of the present invention is preferably a hydrogenation catalyst in which at least one selected from the above Group 8 elements is supported on a carrier. The carrier is not particularly limited, and a carrier usually used as a catalyst carrier can be selected. For example, alumina, activated carbon, silica / alumina such as zeolite, or zirconia is preferable, and activated carbon is particularly preferable from the viewpoint of easy availability. Further, the hydrogenation catalyst is preferably activated carbon supporting palladium, activated carbon supporting an alloy of palladium and gold, activated carbon supporting platinum, or the like. The amount of the Group 8 element supported is not particularly limited, but is preferably 0.01 to 20% by weight, and particularly preferably 1 to 5% by weight, supported in the catalyst. The method for supporting the Group 8 element on the carrier is not particularly limited, and a conventional method for preparing a noble metal catalyst can be applied. Furthermore, it is preferable to carry out a reduction treatment after preparing the catalyst because stable characteristics can be obtained.

The reaction of the present invention may be carried out in the presence of an inert gas. Examples of the inert gas include nitrogen and rare gases. As the rare gas, argon, helium, neon or the like is preferable. Among these, nitrogen or helium is preferable as the inert gas from the viewpoints of ease of handling and availability. The amount of the inert gas is not particularly limited, but if it is too large, the yield may decrease. Therefore, in the usual case, in the vaporized product of the above iodofluorocarbon and hydrogen or a hydrogen-containing organic compound. It is preferable to entrain about 50% by volume or less.

The reaction temperature in the gas phase reaction varies depending on the presence or absence of the hydrogenation catalyst. When the catalyst is not present, about 150 to 600 ° C. is suitable, and particularly 250 to 50 ° C.
0 ° C is preferred. 100-40 if catalyst is present
About 0 ° C. is suitable, and 150 to 350 ° C. is particularly preferable. In any case, when the reaction temperature is low, the reaction conversion rate tends to be low. The reaction time is usually 0.1 to
300 seconds is preferable, and 2 to 60 seconds is particularly preferable. If the reaction time is too short, the conversion rate may be low, while if it is too long, the production of by-products may be increased. When hydrogen is used for the reaction, the reaction pressure is about 0 to 10 atm, preferably 0 to 3 atm in gauge pressure from the viewpoint of safety. Further, when a reducing agent other than hydrogen is used, it is not particularly limited, and it may be any of normal pressure, reduced pressure, or increased pressure, but in a normal case, it is about 0.5 to 5 atm in gauge pressure. Is good.

The hydrofluorocarbon produced by the above reaction is a compound represented by the general formula H _n R _f H. However, in the formula, n is 0 or 1. When n is 0, R _f is a linear or branched polyfluoroalkyl group having 2 to 12 carbon atoms, preferably 3 to 8 carbon atoms, particularly CF ₃ CF ₂ CF ₂ CF ₂ CF. ₂ CF ₂
It is preferably −. When n is 1, R _f is a linear or branched polyfluoroalkylene group having 2 to 12 carbon atoms, preferably 3 to 8 carbon atoms, particularly —CF ₂ CF ₂ CF ₂ CF ₂ It is preferably −.

Specific examples of the hydrofluorocarbon include 1,1,1,2,2-pentafluoroethane F (C
F ₂ ) ₂ H, 1,1,1,2,2,3,3,4,4-nonafluorobutane F (CF ₂ ) ₄ H, 1,1,1,2,
2,3,3,4,4,5,5,6,6-tridecafluorohexane F (CF ₂ ) ₆ H, 1,1,1,2,2
3,3,4,4,5,5,6,6,7,7,8,8- heptadecafluorooctanesulfonic _{F (CF 2) 8 H,} 1,1,
1,2,3,3,3-heptafluoropropane CF ₃ C
FHCF ₃ , 1,1,1,2,3,3,4,4-octafluoro-2-trifluoromethylbutane (CF ₃ ) ₂
CF (CF ₂ ) ₂ H, 1,1,1,2,3,3,4
4,5,5,6,6- dodecafluoro-2-trifluoromethyl-hexane _{(CF 3) 2 CF (CF} 2) 4 H,
1,1,2,2-tetrafluoroethane H (CF ₂ ) ₂
H, 1,1,2,2,3,3,4,4-octafluorobutane H (CF ₂ ) ₄ H, 1,1,2,2,3,3
4,4,5,5,6,6-dodecafluorohexane H
(CF ₂₎ such as ₆ H and the like.

The above reaction of the present invention is an excellent reaction showing an extremely high reaction rate. The obtained reaction crude liquid of hydrofluorocarbon is usually passed through an aqueous alkali solution to remove the produced inorganic iodine compound and the like to obtain a product. The aqueous alkali solution is preferably an aqueous solution of an alkali metal hydroxide, such as sodium hydroxide or potassium hydroxide. Usually, the concentration of the aqueous solution of the alkali metal hydroxide is preferably about 5 to 50% by weight, and particularly preferably 10 to 30% by weight. Further, when it is desired to obtain a higher-purity product, it may be further purified by distillation.

Further, when sufficient purification cannot be achieved by distillation purification, or when a higher-purity hydrofluorocarbon is desired, a reaction crude liquid or a reaction in which an aqueous solution of an alkali metal hydroxide is passed by the above method. It is preferred to treat the product with an alkali metal hydroxide. By treating with an alkali metal hydroxide, impurities contained in the hydrofluorocarbon, particularly various organic iodine compounds derived from the raw material iodofluorocarbon can be efficiently removed. As the alkali metal hydroxide, potassium hydroxide, sodium hydroxide and the like are preferable.
Further, the amount of the alkali metal hydroxide is preferably in a large excess amount with respect to the amount of impurities, and usually, it is preferably about 10 times mol or more with respect to 1 mol of the impurities.

The treatment with the alkali metal hydroxide is usually preferably carried out by heating in the presence of an organic solvent. The organic solvent is not particularly limited, and a known or well-known organic solvent can be adopted. As the organic solvent, alcohols, ethers, ketones and the like are preferable, and particularly,
From the viewpoint of high reactivity and solubility of alkali metal hydroxides, alcohols are preferable.

Examples of alcohols, ethers, and ketones include the same compounds as those described above for the reducing agent, but as the alcohols in the purification step,
Methanol, ethanol, propanol, butanol,
Isopropanol, isobutanol and the like are preferable, and methanol and ethanol are particularly preferable. As ethers, diethyl ether, tetrahydrofuran, 1,4-
Dioxane, ethylene glycol dimethyl ether and the like are preferable, and as the ketones, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetyl ketone and the like are preferable.

The organic solvent may be any one of the above organic solvents or two or more of them. Also,
The amount of the organic solvent is not particularly limited, and is preferably an amount that can dissolve the above alkali metal hydroxide or more.

In general, the treatment temperature is preferably about 0 to 200 ° C., and when an organic solvent is used, the reflux temperature of the solvent is preferable. The temperature can be appropriately changed depending on the type and presence or absence of the organic solvent. The pressure may be reduced pressure, normal pressure or increased pressure, but normal pressure is usually preferable. The processing time is about 0.1 to 10 hours, preferably 0.1 to 2 hours.

The hydrofluorocarbon treated with the alkali metal hydroxide is usually of high purity except for the alkali metal iodide produced by washing with water. Further, if desired, it can be further purified by distillation to obtain a higher purity.

The obtained hydrofluorocarbon has not only a small effect on the environment as compared with the conventionally used chlorinated hydrocarbons or chlorinated fluorinated hydrocarbons, but also has similar uses, for example, a foaming agent, It can also be used as a refrigerant, a cleaning agent, and the like.

Further, the hydrofluorocarbon synthesized by the method of the present invention has a small amount of unreacted iodofluorocarbon and other impurities, and the influence derived from them can be eliminated. Therefore, even when the polymerization reaction is carried out using the hydrofluorocarbon obtained by the above method as a solvent, the reaction can be carried out without coloring the polymer.

The polymer is not particularly limited, but a fluorine-based polymer such as polytetrafluoroethylene, a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, or a copolymer of tetrafluoroethylene and ethylene is particularly preferable.

Further, even when bromofluorocarbon or the like is synthesized using the hydrofluorocarbon synthesized in the present invention as a starting material and used as an artificial blood or a contrast agent, a coloring phenomenon presumed to be derived from an iodine compound is not recognized. There is.

[0042]

EXAMPLES Examples of the present invention will be specifically described below, but the present invention is not limited thereto.

[Examples 1 to 6] A reaction tube made of Inconel 600 having an inner diameter of 2.54 cm and a length of 100 cm was heated in an electric furnace. I (CF ₂ ) ₆ F or I (C as starting materials
F ₂ ) ₈ F or I (CF ₂ ) ₄ I was vaporized by a preheater and introduced into the reaction tube together with hydrogen at atmospheric pressure. At this time, the molar ratio of hydrogen to the starting material was 2: 1 (Examples 1 to 4) or 4: 1.
(Examples 5 to 6), the reaction temperature is 400 ° C. or 45
The temperature in the reaction tube was 0 ° C. and the residence time was 40 seconds. The reaction product passed through a 20% by weight aqueous potassium hydroxide solution and then was cooled to -78
It was collected in a trap cooled to ℃. The collected reaction product was analyzed by gas chromatography and NMR. The results are shown in Table 1.

[0044]

[Table 1]

Example 7 U made of Inconel 600 having an inner diameter of 2.54 cm and a length of 100 cm filled with 200 cc of palladium-supporting activated carbon (palladium-supporting amount: 2% by weight).
The V-shaped reaction tube was immersed in a salt bath furnace. Starting material I (CF
₂ ) ₆ F was vaporized by a preheater and introduced into the reaction tube together with hydrogen at atmospheric pressure. At this time, the molar ratio of hydrogen to the starting material is 2: 1,
The reaction temperature was 250 ° C. and the contact time was 20 seconds. The reaction product passed through a 20 wt% aqueous potassium hydroxide solution and was then collected in a trap cooled to -78 ° C.
The collected reaction product is analyzed by gas chromatography and NMR.
Was analyzed using. The reaction rate of the starting material is 90.3%, H
The selectivity for (CF ₂ ) ₆ F was 98.3%.

[Examples 8 to 10] The reaction temperature was set to 300 ° C, or palladium-supporting activated carbon having a palladium loading of 5% by weight was used as the catalyst, or Pd was used as the catalyst.
A reaction was performed in the same manner as in Example 7 except that an Au alloy (Pd: Au = 9: 1 (weight ratio)) supported on activated carbon in an amount of 2% by weight was used. The results are shown in Table 2.

[0047]

[Table 2]

[Examples 11 to 12] I as a starting material
A reaction was performed in the same manner as in Example 7 using (CF ₂ ) ₈ F (Example 11). A reaction was performed in the same manner as in Example 11 except that the reaction temperature was 300 ° C (Example 1
2). The results are shown in Table 3.

[0049]

[Table 3]

Example 13 As a starting material, I (CF)
₂ ) ₄ I, Pd-Au alloy (Pd: Au =
The reaction was performed in the same manner as in Example 7, except that 2% by weight of activated carbon (9: 1 (weight ratio)) was supported, and the molar ratio of hydrogen to the starting material was 4: 1. Reaction rate is 9
The selectivity was 9.9% and the selectivity was 98.4%.

[Examples 14 to 16] Inner diameter 2.54 cm,
A 100 cm long Inconel 600 reaction tube was heated in an electric furnace. A liquid obtained by mixing I (CF ₂ ) ₆ F and methanol at a molar ratio of 1: 5 was vaporized by a preheater and introduced into the reaction tube at normal pressure. Reaction temperature is 350 ° C, 400 ° C or 450
C. and the residence time in the reaction tube was 20 seconds. The reaction product passed through a 20 wt% sodium hydroxide aqueous solution,
It was collected in a trap cooled to 78 ° C. The results are shown in Table 4.

[0052]

[Table 4]

[Embodiment 17] Inner diameter 2.54 cm, length 1
A 00 cm reaction tube made of Inconel 600 was heated in an electric furnace. I (CF ₂ ) ₆ F and 2-propanol in a molar ratio of 1:
The liquid mixed in 5 was vaporized by a preheater and introduced into the reaction tube at normal pressure. The reaction temperature was 350 ° C., and the residence time in the reaction tube was 20 seconds. The reaction product passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. As a result of analyzing the collected reaction product, the reaction rate was 9
The selectivity was 8.1% and the selectivity was 83.0%.

[Embodiment 18] Inner diameter 2.54 cm, length 1
A 00 cm reaction tube made of Inconel 600 was heated in an electric furnace. A liquid obtained by mixing I (CF ₂ ) ₄ I and methanol at a molar ratio of 1: 5 was vaporized by a preheater and introduced into the reaction tube at normal pressure.
The reaction temperature was 350 ° C., and the residence time in the reaction tube was 20 seconds. The reaction product was passed through a 20 wt% aqueous solution of potassium hydroxide and then collected in a trap cooled to -78 ° C. As a result of analyzing the collected reaction product, 1
The content was 8.3%. The reaction rate was 98.1% and the selectivity was 78.6%.

Examples 19 to 21 Inconel 6 having an inner diameter of 2.54 cm and a length of 100 cm filled with 200 cc of palladium-supporting activated carbon (palladium-supporting amount: 2% by weight).
A U-shaped reaction tube manufactured by 00 was immersed in a salt bath furnace. I (CF
₂ ) A liquid obtained by mixing ₆ F and methanol in a molar ratio of 1: 5 was vaporized by a preheater and introduced into the reaction tube at normal pressure. Reaction temperature is 2
The contact time is 20 ° C and the temperature is 00 ° C, 250 ° C or 300 ° C
It was seconds. The reaction product passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. The results are shown in Table 5.

[0056]

[Table 5]

Example 22 The reaction was performed in the same manner as in Example 19 except that the amount of palladium loaded on the palladium-supporting activated carbon was 5% by weight and the reaction temperature was 250 ° C. The reaction rate was 100.0% and the selectivity was 98.0%.

[Examples 23 to 24] Inconel 6 having an inner diameter of 2.54 cm and a length of 100 cm filled with 200 cc of palladium-supporting activated carbon (palladium-supporting amount: 2% by weight).
A U-shaped reaction tube manufactured by 00 was immersed in a salt bath furnace. I (CF
₂ ) A liquid obtained by mixing ₆ F and ethanol in a molar ratio of 1: 2 was vaporized by a preheater and introduced into the reaction tube at normal pressure. Reaction temperature is 2
The temperature was set to 00 ° C or 250 ° C, and the contact time was 20 seconds. The reaction product passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. The results are shown in Table 6.

[0059]

[Table 6]

[Embodiment 25] Inner diameter 2.54 cm, length 1
A 00 cm reaction tube made of Inconel 600 was heated in an electric furnace. A liquid obtained by mixing I (CF ₂ ) ₆ F, methanol and 2-propanol at a molar ratio of 1: 1: 1 was vaporized by a preheater and introduced into the reaction tube at normal pressure. The reaction temperature was 350 ° C., and the residence time in the reaction tube was 40 seconds. The reaction product passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. As a result of analyzing the collected reaction product, the reaction rate was 81.4% and the selectivity was 92.0%.

[Examples 26 to 29] Inner diameter 2.54 cm,
A 100 cm long Inconel 600 reaction tube was heated in an electric furnace. I (CF ₂ ) ₆ F and ethanol in a molar ratio of 1:
The liquid mixed in 2 is vaporized by a preheater and further
0% concentration (volume concentration) of nitrogen was entrained and introduced into the reaction tube at normal pressure. Reaction temperature is 335 ° C, 350 ° C, 370 ° C
Alternatively, the temperature was 400 ° C., and the residence time in the reaction tube was 40 seconds. The reaction product passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. The collected reaction product was analyzed. The results are shown in Table 7.

[0062]

[Table 7]

[Examples 30 to 33] Inner diameter 2.54 cm,
A 100 cm long Inconel 600 reaction tube was heated in an electric furnace. I (CF ₂ ) ₆ F and formic acid in a molar ratio of 1: 2.
Each was vaporized in a preheater at a rate of 5 and introduced into the reaction tube at normal pressure. The reaction temperature was 360 ° C, 380 ° C, 400 ° C or 420 ° C, and the residence time in the reaction tube was 30 seconds.
The reaction product passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. The collected reaction product was analyzed. The results are shown in Table 8.

[0064]

[Table 8]

[Embodiment 34] Inner diameter 2.54 cm, length 1
A 00 cm reaction tube made of Inconel 600 was heated in an electric furnace. I (CF ₂ ) ₄ I and formic acid were vaporized in a preheater at a molar ratio of 1: 2.5, respectively, and introduced into the reaction tube at atmospheric pressure.
The reaction temperature was 420 ° C., and the residence time in the reaction tube was 40 seconds. The reaction product passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. As a result of analyzing the collected reaction product, the monoiodo form was found to be 1.2.
% Was included. The reaction rate is 99.5% and the selectivity is 96.
It was 1%.

[Example 35] 2.54 inner diameter filled with 300 cc of granular activated carbon (granular egret activated carbon manufactured by Takeda Pharmaceutical Co., Ltd.)
Inconel 600 U-shaped reaction tube having a length of 100 cm and a length of 100 cm was immersed in a salt bath furnace. I (CF ₂ ) ₆ F and formic acid were vaporized in a preheater at a molar ratio of 1: 1.5 and introduced into the reaction tube at atmospheric pressure. The reaction temperature was 300 ° C., and the residence time in the reaction tube was 30 seconds. The reaction product passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. As a result of analyzing the collected reaction product,
The reaction rate was 100% and the selectivity was 97.7%.

[Examples 36 to 38] Palladium-supporting activated carbon (palladium-supporting amount: 2% by weight or 5% by weight) 20
A U-shaped reaction tube made of Inconel 600 having an inner diameter of 2.54 cm and a length of 100 cm filled with 0 cc was immersed in a salt bath furnace. I (CF ₂ ) ₆ F and formic acid were vaporized in a preheater at a molar ratio of 1: 2.5 and introduced into the reaction tube at atmospheric pressure. The reaction temperature was 200 ° C. or 250 ° C., and the contact time was 20 seconds. The reaction product passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. The collected reaction product was analyzed. The results are shown in Table 9.

[0068]

[Table 9]

[Embodiment 39] Inner diameter 2.54 cm, length 1
A 00 cm reaction tube made of Inconel 600 was heated in an electric furnace. I (CF ₂ ) ₆ F and formic acid are vaporized in a preheater at a molar ratio of 1: 2.5, respectively, and further 20% concentration (volume concentration) of nitrogen of all vaporized substances is entrained, and the reaction tube is operated under normal pressure. Introduced. The reaction temperature was 440 ° C., and the residence time in the reaction tube was 40 seconds. The reaction product passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. As a result of analyzing the collected reaction product, the reaction rate was 9
The selectivity was 9.9% and the selectivity was 97.2%.

[Examples 40 to 41] Inner diameter 2.54 cm,
A 100 cm long Inconel 600 reaction tube was heated in an electric furnace. I (CF ₂ ) ₆ F and dioxane were vaporized in a preheater at a molar ratio of 1: 2 and introduced into the reaction tube at atmospheric pressure. The reaction temperature is 350 ° C or 400 ° C,
The residence time in the reaction tube was 30 seconds. 20 reaction products
After passing through a potassium hydroxide aqueous solution of wt%, it was collected in a trap cooled to -78 ° C. The results are shown in Table 10.

[0071]

[Table 10]

[Examples 42 to 49] The reaction was performed in the same manner as in Example 40 except that the reducing agents and reaction temperatures shown in Table 11 were used. Table 11 shows the analysis results of the reducing agent used, the reaction temperature, and the collected product.

[0073]

[Table 11]

[Embodiment 50] Inner diameter 2.54 cm, length 1
A 00 cm Inconel 600 reaction tube was heated in an electric furnace. A liquid obtained by mixing I (CF ₂ ) ₆ F as a starting material and ethanol in a molar ratio of 1: 2 was vaporized by a preheater and introduced into the reaction tube at normal pressure. The reaction temperature was 380 ° C., and the residence time in the reaction tube was 30 seconds. The reaction product was passed through a 20 wt% potassium hydroxide aqueous solution and then collected in a trap cooled to -78 ° C. As a result of analyzing the recovered reaction crude liquid by gas chromatography, H (CF ₂ ) ₆ F [boiling point 71
℃] 88.5%, ethyl iodide [boiling point 72 ℃] 5.7
%, Ethyl acetate [boiling point 77 ° C.] 3.5%, diethyl ether 1.3%, unreacted starting material 0.1%, and other impurities 0.9%.

Reference Example 1 A 2-liter four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer was used.
256 g of methanol, 30 g of 2-propanol, 8
74.3 g (1.13 mol) of 5% potassium hydroxide was charged. After heating the reactor to an internal temperature of 60 ° C., 1500 g of the reaction crude liquid obtained in Example 50 was added dropwise over 1 hour.
After the dropping was completed, heating and refluxing were continued for 2 hours. After cooling the reactor to room temperature, 300 g of water was added to dissolve the precipitated potassium iodide. The reaction crude liquid was separated into two layers, and the fluorocarbon layer (lower layer) was further washed with 500 g of water. When the fluorocarbon layer was analyzed, the purity of C ₆ F ₁₃ H was 9
It was 8.3%, ethyl iodide and ethyl acetate were not detected, and the amount of unreacted starting material was 10 ppm or less.
Next, the obtained fluorocarbon layer was distilled using a distillation column having 5 theoretical plates to obtain a purity of 99.99.
1240 g of 5% C ₆ F ₁₃ H was obtained. The obtained C ₆ F ₁₃
As a result of analyzing H, no unreacted starting material was detected.

[0076]

According to the present invention, hydrofluorocarbons can be produced with a very good reaction rate and selectivity at low pressure and in a short time. Further, the method of the present invention is an industrially very advantageous method because it is a continuous gas phase reaction and does not require any special reagents or operations. Further, the obtained hydrofluorocarbon can be made even more highly pure by only a simple purification treatment.

Claims (11)

[Claims] 1. A general formula I _n R _f I (wherein n is 0
Or 1 and n is 0, R _f has 2 to 12 carbon atoms.
Is a linear or branched polyfluoroalkyl group, and when n is 1, R _f is a linear or branched polyfluoroalkylene group having 2 to 12 carbon atoms. ), An iodofluorocarbon represented by the general formula H _n R characterized by reacting in a gas phase under the action of a reducing agent.
_A method for producing a hydrofluorocarbon represented by _f H (wherein n and R _f have the same meanings as described above). 2. The method according to claim 1, wherein the reducing agent is an organic compound having a hydrogen atom bonded to a carbon atom or hydrogen. 3. Organic compounds are alcohols, glycols, carboxylic acids, carboxylic acid derivatives, ethers,
The method according to claim 2, which is at least one organic compound selected from the group consisting of ketones and hydrocarbons. 4. The method according to claim 2, wherein the organic compound is an alcohol having 1 to 3 carbon atoms or a carboxylic acid having 1 to 3 carbon atoms. 5. The organic compound is methanol, ethanol,
Alternatively, it is formic acid. 6. The production method according to claim 1, wherein the reaction is carried out in the absence of a catalyst. 7. The production method according to claim 1, wherein the reaction is carried out in the presence of a hydrogenation catalyst. 8. The method according to claim 7, wherein the hydrogenation catalyst is a hydrogenation catalyst containing at least one selected from the group consisting of alumina, activated carbon, zeolite, and Group 8 elements. 9. The method according to claim 7, wherein the hydrogenation catalyst is palladium or a catalyst containing palladium and gold or silver. 10. n is 0 and R _f is CF ₃ CF ₂ CF.
₂ CF ₂ CF ₂ CF ₂ - a method of making any of claims 1 to 9. 11. n is 1 and R _f is --CF ₂ CF ₂ C.
F ₂ CF ₂ - a method of making any of claims 1 to 9.